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// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package org.apache.doris.nereids.trees.expressions.functions.scalar;

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.BigIntType;
import org.apache.doris.nereids.types.BitmapType;
import org.apache.doris.nereids.types.BooleanType;
import org.apache.doris.nereids.types.DateTimeType;
import org.apache.doris.nereids.types.DateTimeV2Type;
import org.apache.doris.nereids.types.DateType;
import org.apache.doris.nereids.types.DateV2Type;
import org.apache.doris.nereids.types.DecimalV2Type;
import org.apache.doris.nereids.types.DecimalV3Type;
import org.apache.doris.nereids.types.DoubleType;
import org.apache.doris.nereids.types.FloatType;
import org.apache.doris.nereids.types.IntegerType;
import org.apache.doris.nereids.types.LargeIntType;
import org.apache.doris.nereids.types.SmallIntType;
import org.apache.doris.nereids.types.StringType;
import org.apache.doris.nereids.types.TinyIntType;
import org.apache.doris.nereids.types.VarcharType;
import org.apache.doris.nereids.util.ExpressionUtils;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * ScalarFunction 'coalesce'. This class is generated by GenerateFunction.
 */
public class Coalesce extends ScalarFunction
        implements ExplicitlyCastableSignature {

    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.ret(BooleanType.INSTANCE).varArgs(BooleanType.INSTANCE),
            FunctionSignature.ret(TinyIntType.INSTANCE).varArgs(TinyIntType.INSTANCE),
            FunctionSignature.ret(SmallIntType.INSTANCE).varArgs(SmallIntType.INSTANCE),
            FunctionSignature.ret(IntegerType.INSTANCE).varArgs(IntegerType.INSTANCE),
            FunctionSignature.ret(BigIntType.INSTANCE).varArgs(BigIntType.INSTANCE),
            FunctionSignature.ret(LargeIntType.INSTANCE).varArgs(LargeIntType.INSTANCE),
            FunctionSignature.ret(FloatType.INSTANCE).varArgs(FloatType.INSTANCE),
            FunctionSignature.ret(DoubleType.INSTANCE).varArgs(DoubleType.INSTANCE),
            FunctionSignature.ret(DateTimeType.INSTANCE).varArgs(DateTimeType.INSTANCE),
            FunctionSignature.ret(DateType.INSTANCE).varArgs(DateType.INSTANCE),
            FunctionSignature.ret(DateTimeV2Type.SYSTEM_DEFAULT).varArgs(DateTimeV2Type.SYSTEM_DEFAULT),
            FunctionSignature.ret(DateV2Type.INSTANCE).varArgs(DateV2Type.INSTANCE),
            FunctionSignature.ret(DecimalV3Type.WILDCARD).varArgs(DecimalV3Type.WILDCARD),
            FunctionSignature.ret(DecimalV2Type.SYSTEM_DEFAULT).varArgs(DecimalV2Type.SYSTEM_DEFAULT),
            FunctionSignature.ret(BitmapType.INSTANCE).varArgs(BitmapType.INSTANCE),
            FunctionSignature.ret(VarcharType.SYSTEM_DEFAULT).varArgs(VarcharType.SYSTEM_DEFAULT),
            FunctionSignature.ret(StringType.INSTANCE).varArgs(StringType.INSTANCE)
    );

    /**
     * constructor with 1 or more arguments.
     */
    public Coalesce(Expression arg, Expression... varArgs) {
        super("coalesce", ExpressionUtils.mergeArguments(arg, varArgs));
    }

    /**
     * custom compute nullable.
     */
    @Override
    public boolean nullable() {
        for (Expression argument : children) {
            if (!argument.nullable()) {
                return false;
            }
        }
        return true;
    }

    /**
     * withChildren.
     */
    @Override
    public Coalesce withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() >= 1);
        return new Coalesce(children.get(0),
                children.subList(1, children.size()).toArray(new Expression[0]));
    }

    @Override
    public List<FunctionSignature> getSignatures() {
        return SIGNATURES;
    }

    @Override
    public <R, C> R accept(ExpressionVisitor<R, C> visitor, C context) {
        return visitor.visitCoalesce(this, context);
    }
}
